The study of damage to the DNA of living organisms and the cellular responses to such damage constitute a cornerstone of modern molecular biology and medicine. The study of DNA repair in prokaryotes such as Escherichia coli paved the way for exploration in other organisms. DNA repair has since been identified as a biological phenomenom on occurring at every level of biological organization, including humans. Studies in the latter have revealed the existence of specific human diseases with proven or suspected defects in DNA repair and have suggested a distinct correlation between DNA damage and carcinogenesis. The last occasion in which an international group of authorities in this field met to discuss the topics of DNA damage and repair was in 1978. The 1983 meeting proposes to bring this concentration of expertise together in a focused format that will consider numerous aspects of the molecular biology, biochemistry and molecular pathology of DNA damage. Discussion will take the form of plenary sessions, workshops and poster sessions with large amounts of free time to encourage informal debate and information exchange. It is anticipated that this meeting will be maximally attended and that the program will serve to stimulate continued research in already established areas and develop new directions for research on how living organisms respond to perturbations in genetic information produced by DNA damage.